- A broad strongly calcified plate in front of, and above, the mouth. It represents the fused sternites of the third and fourth segments [Warner, 1977].A transverse plate situated anterior to the mouth [Hobbs, Hobbs, and Daniel 1977].Antennal sternum mainly represented by epistome, a plate of varying shape lying between labrum and bases of antennae. In shrimps, comparatively narrow and separated on each side from lateral portions of carapace by exhalant branchial channels. In Astacidea and Anomura, broad and in contact with carapace on each side; in Brachyura, becoming firmly united with carapace. The epistome forms the anterior part of the buccal frame [Williams, 1984].Front part of head above labrum, sometimes produced anteriorly into a spine [Holdich and Jones, 1983].Plate of varying shape between labrum and bases of antennae in brachyuran decapods, also defined as sternum of antennal somite [Moore and McCormick, 1969].Plate of varying shape between labrum and bases of antennae; also sternum of antennal somite [McLaughlin, 1980].Region of carapace between front of carapace, antennules and buccal region [Poore, 2004].The transverse plate anterior to the mouth area in crayfishes and crabs [Chace and Hobbs, 1969].The transverse plate forming the anterior border of the buccal frame, laterally fused with the carapace and (usually), anteriorly fused with the front [Ingle, 1983].Transverse plate (usually somewhat triangular in shape) situated ventrally and anterior to gnathal appendages of crayfishes (see Fig. 23i) [Hobbs and Jass, 1988].Transverse plate anterior to mouth area [Perez Farfante and Kensley, 1997].(Order Diplostraca):Rostrum [Stachowitsch, 1992].(Order Cumacea):On underside of head, pair of small plates between bases of antennules. Adjoined posteriorly by upper lip (labrum) [Stachowitsch, 1992].(Order Decapoda):Relatively large, plate-like structure in front of mouth on underside of head. May be divided into more narrow anterior part extending between antennae and broader posterior portion (endostome). Adjoined posteriorly by labrum. Also considered to be sternum of second cephalic segment (antennal somite). See: metapon [Stachowitsch, 1992].(Order Amphipoda):On underside of head, plate-like structure in front of upper lip (labrum). (pointed, rounded) [Stachowitsch, 1992].(Order Stomatopoda):Relatively large, plate-like structure in front of mouth on underside of head (cephalon); adjoined posteriorly by labrum [Stachowitsch, 1992].
Crustacea glossary. Natural History Museum of Los Angeles County. 2011.